The present invention relates generally to multistrata absorbent composites and, in particular, to unitary composites having individual strata separated by transition zones.
Currently, diapers are manufactured using individual materials and layers that are designed for a specific functionality. In addition to a liquid pervious topsheet and a liquid impervious backsheet, a typical diaper includes a multilayered absorbent structure. The absorbent structure has an acquisition layer for rapidly acquiring a liquid insult, optionally a distribution layer for receiving and distributing liquid acquired from the acquisition layer, and a storage layer for retaining the acquired liquid. These individual layers are assembled on a production line to provide a diaper having a multilayered absorbent core. Not surprisingly, the nature of the interface between these layers affects the product""s performance characteristics and functionality. For diapers assembled on a typical diaper production line, there exists a substantial discontinuity between the materials of each layer resulting in a disruption of the liquid communication between these layers, ultimately impeding liquid transfer between these layers. Problems associated with discontinuities between the materials of adjacent layers is ordinarily reduced by using adhesives. However, adhesives tend to hinder liquid transfer.
Accordingly, there exists a need for an absorbent composite for use in an absorbent articles such as a diaper in which the composite""s component layers are in intimate liquid communication such that transfer of liquid between the layers is not hindered. A need also exists for methods for forming such absorbent composites.
In one aspect, a unitary composite is disclosed that includes a plurality of strata in which adjacent strata are separated by a transition zone integrally connecting the strata. Each stratum of the composite preferably includes fibers and a binder. Each transition zone includes fibers from adjacent strata. Preferred composites include from two to five strata. In other aspects, absorbent articles that incorporate the unitary composite and methods for forming the unitary composite are also disclosed.